Utils: Remove one LayoutBuilder::addRow() overload

The flexibility here is getting in the way later when trying to
remove the dependency on aspects.

Change-Id: I7221e80f2067292c7c80aead8f6d739fb7878f7e
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/libs/utils/layoutbuilder.h

@@ -188,7 +188,6 @@ public:
     LayoutBuilder &addItems(const LayoutItems &items);
 
     LayoutBuilder &finishRow();
-    LayoutBuilder &addRow(const LayoutItem &item);
     LayoutBuilder &addRow(const LayoutItems &items);
 
     LayoutType layoutType() const { return m_layoutType; }